The new Coronavirus is transmitted primarily through droplets and aerosols, is now well known. The nose is already since a long time as a possible Main entry point. American researchers to the presumption under walls – by klonten the Virus, and lights brought in.
In most cases, people with Coronavirus-induced disease Covid-19 by droplet infection to put. That is, the pathogens are passed from the throat, nose, or throat of an infected person via small droplets to other people. This is what happens when an Infected person coughs, for example, sneezes or speaks. The droplets, which he emits in the process, can reach the mucous membranes of the nose or mouth of a healthy person and infect.
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What is the most important portal of Entry is whether the nose or the throat, was unclear. By the end of April, a team of researchers had suspected on the basis of study results, that cells of the nose are the most likely routes of Entry for the Virus. Now the US has supported team of researchers the results.
The scientists Yixuan Hou of the University of North Carolina examined on the basis of an innovative method of how Sars-CoV-2 spread in the body. They found The fastest way to the Virus propagated in the nose. Their results were published in the scientific magazine “Cell”.
Researchers brought in Sars-CoV-2 to the lights – and watched as it multiplied
For their study, the researchers constructed on the basis of existing genome data an artificial Sars-CoV-2 Virus. This was brought about by a fluorescent light to glow green.
Then, the researchers infected cell cultures from the nose, bronchi and lungs, and tracked using the glowing cells, how quickly they multiplied in each case. They saw that the Virus spread in the ciliated cells in the nose many times faster than in the lower respiratory tract: within 24 hours there was in the nose cells, significantly higher virus titers.
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In addition, the researchers used a highly sensitive method for the quantification of the amount of the entry receptor ACE2. They observed that the number of ACE2 receptors along the way from the upper to the lower respiratory tract decreased, and that the Virus was able to infect the upper respiratory tract better. Both in the upper Airways and in the bronchial mucosa, especially the cilia of the cells were affected by the infection.
The relatively high rate of infection of the nasal mucosa brought the researchers to the conclusion that the Virus attacks first the cells of the nasal cavity and from there via body fluids in deep areas of the lung. The flicker would be hairs in the nose and throat the Virus to the nasal mucosa and the pharynx down to transport. There it accumulates, until it is swallowed.
At night, the mucus may be sucked in also through the respiratory air in the lungs, when the Reflex to Close the nasopharynx is absent during Swallowing, a phenomenon which is also well-known risk groups such as diabetics, Elderly and Overweight a typical Symptom.
Infection works best on cells in the nasal mucosa
“With the sensitive detection of ACE2 receptors and Infection experiments, it can be shown that the infection works much better to cells of the nasal mucous membrane, as in cells of the bronchial mucosa, probably to the nasal mucosa begins. It is and can’t be closed, that the other way occur in the direct infection of the lungs – as well. This way but the results implausible,“ says Bernd Salzberger, head of infectious diseases at the University hospital Regensburg.
In a second part of the study, the researchers investigated whether already known antibodies could attack from the past Mers – and Sars-epidemics of the new Virus, i.e. whether a so-called cross-reactivity. The researchers found that antibodies found in the blood of Sars patients, were able to inhibit to a small extent, the propagation of Sars-CoV-2 in the laboratory. Similar observations made in the past, researchers at the Berlin Charité, which found that past colds can cause a Coronavirus cross-reactivity.
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German scientists from the methodology, thrilled
German scientists are expressed in terms of the study, especially compared with the laboratory-created, fluorescent Virenklons positive. This would offer large potential for further pathological, immunological, or virological studies of Sars-CoV-2: “This is a very interesting study, especially because of the elegant method of the recombinant viruses with fluorescent properties, which can make the infection of specific cells is visible, and thus, the research brings,” says Salzberger.
There were also critical voices
But there are also critical voices. Wolfgang Kummer, Director of the Institute for anatomy and cell biology, Justus-Liebig-University of Giessen explains, the work is important for the specialized world, “but starts the same as the proof for catchy theses such as ‘the infection with the infection of a particular cell type (ciliated supporting cell) in the nose and spreads from there, with the inhalation air is gradually up in the pulmonary alveoli’ count.”
He complains, moreover, that the core statements was part of were based only on three individual experiments and in several cases, the number of experiments is not to understand at all – “for such a journal that is extremely amazing.”
Grief but also emphasizes that each method of investigation “with their own, inevitable limitations and sources of error” have. To hedge of data confirmation experiments are also over a longer period of time is required.
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